The present invention relates generally to devices, systems and methods for material fixation, and, more particularly, to suture management and tensioning devices used during soft tissue reconstruction or bone-to-bone fixation that will assist in the repair of many soft tissue injuries, such as in the reconstruction of the Anterior Cruciate Ligament (ACL).
Prior to completing the final steps of fixation during an ACL repair, the reconstructed ligament must be tensioned in order to establish joint stability. Current devices used to establish ligament pretension require the practitioner to apply and maintain a manual tensile force of the graft during tibial fixation. Devices relying on this technique have proven to be cumbersome, and oftentimes require time consuming steps to prepare the suture component of the tensioning process. These devices also require unnecessary physical exertion, and often require an additional assistant during the final phases of graft fixation. Still other ligament tensioning devices require external fixturing and/or modification of the bone surface to support the tensioning process.
Studies have shown that the magnitude of tension affects characteristics such as the maximal anterior translation or subluxation of the joint. In one study, it was found that a higher graft pretension significantly reduced postoperative anterior-posterior knee laxity. However, optimal tensioning of the reconstructed ligament may be related to graft stiffness, and different ligament reconstruction systems and graft tissue types create different stiffness values. Additionally, the optimal graft tension for men and women may be different. According to a second study, too high of an initial tension may increase the anterior-posterior knee laxity in women though the specific effects of differing graft tensions between genders is unknown. Further research in this area may find an optimal pretension value for each sex.
The tendons of the Gracilis and Semitendinosus muscles are commonly harvested for use in ACL reconstruction. The tendons are doubled over to create a four strand graft complex. During ACL reconstruction the strands are sutured to form a paired complex of either of two strands sutured together. The strength and stiffness of the graft complex typically surpass that of the native ACL, and both characteristics are optimized when a relatively even tension is applied to each of the four tendon strands.
The ConMed™ Linvatec Stress Equalization (SE™) Graft Tensioning System is a soft tissue graft tensioning system with the ability to apply different tensions to either of two sides of a graft in order to equalize stress in grafts of non-uniform diameter. The system requires multiple accessories and additional drill holes to fixate the system within the bone so that tension can be established.
The DePuy Mitek Tie Tensioner is a soft tissue graft tensioning device that requires the user to manually apply and maintain a force distal to the patient. Even tension can be achieved with this device, but requires that the suture ends be tied together to form two loops of equal length. Furthermore, limitations in the range of motion of the device's swiveling suture slide can prohibit true equality in graft strand tension. The Bio-INTRAFIX Surgical Technique manual specifies that the Tie Tensioner be used to manually apply a force of approximately 40 lbs. to the sutures while the knee is cycled to eliminate graft creep. This level of exertion often requires an additional assistant to pull the Tie Tensioner while the knee is cycled. After cycling the knee, the surgeon must maintain a force of at least 10 lbs. while the Intrafix sheath is inserted and screwed into place. Furthermore, the sheath must usually be hammered into place while tension is maintained, often requiring the assistance of an additional technician.